Involuntary Attention in Healthy Older Adults at Electroencephalographic Risk of Cognitive Decline: An ERP Study

The aging of the global population underscores the urgent need for the validation of biomarkers that can reliably distinguish individuals at risk of neurocognitive disorders. While quantitative EEG (qEEG) studies suggest that excessive theta activity predicts cognitive decline in the long term, less is known about whether increased theta can index current reduced cognitive resources, including attention, in older adults.

This study compared the distraction event-related potential (Mismatch Negativity (MMN)-P3a-Reorientation Negativity (RON)), linked to involuntary attention, between 25 older adults with excessive theta activity (risk group, RG) and 25 controls (CG). Participants underwent an auditory duration discrimination task with standard and deviant tones while an EEG was recorded.

Behaviorally, both groups showed distraction effects, with no significant differences between them. There were no significant differences in the amplitudes of the distraction potential between groups. However, the RG exhibited delayed P3a latencies at midline centroparietal regions and delayed RON at left parietal regions. Topographically, the RG displayed a bilateral RON effect (vs. the CG's right-lateralized distribution). The MMN latency remained unaffected.

These findings suggest delayed attentional orientation (P3a) and reorientation (RON) in at-risk adults, despite preserved behavioral performance. The atypical RON distribution may reflect compensatory mechanisms mitigating cognitive inefficiencies. While at-risk-related neural delays did not yet manifest behaviorally, they highlight early electrophysiological markers of subclinical attentional decline. This underscores the utility of increased theta activity in detecting preclinical alterations, challenging the reliance on neuropsychological tests alone.